The invention pertains to capacitor constructions and methods of forming capacitors. In a particular aspect, the invention pertains to crown capacitor constructions.
A method of forming a prior art crown capacitor construction is described with reference to FIGS. 1 and 2. Referring to FIG. 1, a semiconductive material wafer fragment 10 comprises a substrate 12 which supports an electrical node 14. Substrate 12 can comprise, for example, lightly doped monocrystalline silicon. Electrical node 14 can comprise, for example, a conductively-doped diffusion region provided within a monocrystalline silicon substrate 12.
To aid in interpretation of the claims that follow, the terms xe2x80x9csemiconductive substratexe2x80x9d and xe2x80x9csemiconductor substratexe2x80x9d are defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term xe2x80x9csubstratexe2x80x9d refers to any supporting structure, including, but not limited to, the semiconductive substrates described above.
An insulative layer 16 is formed over substrate 12. Insulative layer 16 can comprise, for example, silicon dioxide, silicon nitride, borophosphosilicate glass (BPSG), or phosphosilicate glass (PSG). Layer 16 has an opening 18 extending therethrough to electrical node 14. A conductive plug 20 is provided within opening 18. Conductive plug 20 can comprise, for example, a metal, or conductively doped polysilicon.
A container-shaped storage node 22 is provided over insulative layer 16, and over conductive plug 18. Storage node 22 is in electrical connection with electrical node 14 through conductive plug 18. Container-shaped storage node 22 can also be referred to as a crown-shaped storage node. Storage node 22 comprises upwardly extending members 21, and a horizontally extending member 23.
Referring to FIG. 2, a dielectric material 24 is provided over storage node 22, and a second capacitor electrode layer 26 is provided over dielectric material 24. Dielectric material 24 can comprise, for example, a combination of silicon dioxide and silicon nitride. Alternatively, dielectric material 24 can comprise tantalum pentoxide. Second capacitor electrode 26 can comprise, for example, a metal, conductively doped polysilicon, or a metal-comprising compound, such as, for example, titanium nitride.
Storage node 22, dielectric material 24, and second capacitor electrode 26, together define a crown capacitor.
A problem with the processing described above with reference to FIGS. 1 and 2 is that the upwardly extending members 21 of storage node 22 can be easily broken during subsequent processing. It would therefore be desirable to develop alternative methods of forming crown capacitors.
In one aspect, the invention encompasses a method of forming a capacitor. A mass is formed over an electrical node. An opening is formed within the mass. The opening has a lower portion proximate the node and an upper portion above the lower portion. The lower portion is wider than the upper portion. A first conductive layer is formed within the opening and along a periphery of the opening. After the first conductive layer is formed, a portion of the mass is removed from beside the upper portion of the opening while another portion of the mass is left beside the lower portion of the opening. A dielectric material is formed over the first conductive layer, and a second conductive layer is formed over the dielectric material. The second conductive layer is separated from the first conductive layer by the dielectric material.
In another aspect, the invention encompasses a capacitor construction. Such construction includes an insulative mass over an electrical node, and an opening extending through the mass to the electrical node. The construction further includes a storage node layer within the opening. The storage node layer extends around a periphery of the opening and protrudes above the insulative mass. The storage node layer defines a container shape having a void extending therein. The void has a lower portion within the opening and an upper portion above the opening. The upper portion of the void is narrower than the lower portion. Additionally, the construction includes a dielectric material within the void and partially filling the void, and a second capacitor electrode within the void and separated from the first conductive layer by the dielectric material.